Radio station selector



May 20, 1941. COHEN ETAL 2 2,2 7

I mm sunon SELECTOR Filed larch 4, 1938 3 Shoots-Shut 1 ATTORNEYS 'May 20, 1941.-- a HEN ETAL I v 2,242,281

' RADIO STATION, SELECTOR Filed March '4, 1938 s Sheets-Sheet s Ti|:|.5 I6 4 I7 I 2 I i t I Ticlz. 57

. INVENTORS f JJMOEL COKE/Y ATTORNEYS vfrequency or station.

One of the serious problems in the design of Patented May 20, 1941 aamo s'rATroN smo'ron Samuel Cohen, Brooklyn, N. Y., and Earl 11. Allen,

, Fanwood, N. 1., asslgnors, by memo III!!!- ments, to Condenser Development corporation,

- Newark, N. 1., a corporation or New Jersey Al plication March 4, 1938. Serial No. 193,886

2 Claims.

This invention relates to a radio station selector and more particularly to one in which pushbutton manuals, each-representing a given frequency or station, are selectively operable for actuating the tuning unit of the radio receiver.

The broad prime object of the present invention centers about the provision of a push-button type of tuning selector for a radio receiver designed to operate mechanically in a way to meet the high accuracy requirements of repeatable tuning selection. A corollary prime object of the invention deals with the provision of such a selector which is mechanically simple in con struotion, capable of being reliably manufactured by quantity production methods and possessing long usage life under conditions.

A number of correlated problems are involved in designing a push button selector of this character to meet the stated requirements. The selector of the present invention is intended for v use with a variable tuning unit such as a variable condenser, the rotor of which is movable over an are of 180 degrees. In the selector of the invention, the said rotor is connected to an operating member which is common to and operable by any of a plurality of translationally movable push-button elements each representing a given such a push-button selector is that converting and multiplying the relatively short linear or translational movement of the push-button manuals or elements'into the available 180 degr'ee rotation of the rotor of the tuning unit. This entails the provision of suitable mechanism which will readily convert and multiply short linear movements into a 180 degree rotation and one which can accomplish this, moreover, with that freedom of play and backlash and with that is severe operating -means that at an average point in the tuning range, the rotor should be mechanically tunable by the selector over a 1 degree tolerance. Since the mechanism employed functions not onlyto convert motion but to multiply the same, it becomes'apparent that the push-button manuals and the operating memberof the mechanism must respond to even a higher degree of mechanical operating refinement than the condenser rotor. By means of .the principles underlying the functioning of the apparatus of the present invention, these problems are effectively solved, and in fact it has been ascertained that the tuning accuracy of the selector mechanism is even greater than this described desirable tolerance.

'The more important phase ofthis totalaccuracy" is that of "repeat accuracy," which may be defined as the ability to reproduce a predeter mined setting or tuning over repeated cycles-oi. movement or operation. of the selector mechanism. To eflfectively accomplish the desired repeat acouracy, .the mechanical linkage between a push-button manual and the condenser rotor must be designed to absolutely eliminate play and back lash at all points and with a minimum of friction loss. These requirements are all the more severe due to the motion converting and um of friction loss in the mechanism whichwill permit the obtaining oi high accuracy repeatable operations. One of the main objects of thepresent invention has to do with the proper design of such a motion converting and multi-' plying mechanism.

Two of, the ultimate aims of the invention are to meet the needs-of hightuning accuracy and repeat accuracy. The mean value of tolerance for total accuracy (tuning and repeat accuracy) ured at the condenser rotor) is a tuning variation of plus or minus 1, kilocycle (a total of 2 kilocycles). with a modern variable condenser. employed as the tuning unit of the system, this desirable in the push-button selector (as measmultiplying functioning of the linkage. between any given manual and the condenser rotor, since any error in the mechanical movement (and re- Producibility of suchmovement) of the manual 1 is multiplied at the condenser rotor. By means of the selector structure of the present invention, these problems are eflectively solved and a high repeat accuracy is obtained.- Ithas been determined that with the seleotorstructure of the present invention, repeat accuracy of the condenser rotor does not exceed a 400 cycle range. Obviously, the equivalent repeat frequency accuracy or the operating member and the manual is even higher and comes within a lilo-cycle range.

In a radio station selector, provision must be made to enable the user to adjust or readjust the push button manuals to desired frequencies or stations. It is a further object o! the present invention to provide a station selector in which such adjusment may be made by the user or operator from the outside of the radio cabinet. The adjusting means should desirably be related to the push-button manuals so that besides both being readily accessible to the user exteriorly of the radio cabinet, they'be also mechanically. associated in an efllcient as well as an attractive way'while permitting of action or operation of? one independent of the other. Also, since the adjusting means of necessity forms one of the elements (adjustable) in the linkage between the push-button and the ultimately operated condenser rotor, it is a further requirement of the structural combination that each adjusting means be related to its associated push-button manual, so that the high tuning and repeat accuracies mentioned may neventheless be secured. It is, therefore, a further object. of the invention to provide a selector structure which solves these additional problems.

A further object: of the inventioncenters about the provision of a push-button type of radio tuning selector in which at least one of the pushbutton manuals is designed so as to be capable of being used for operating the tuning unit over its entire tuning rangeto enable the set to be tuned to any desired frequency. The provision of a selector structure in which push-button manuals for preselecting a station is appropriately combined with means for tuning a 'radio set to any desired frequency or station, is desirably accomplished by the mechanism of the present in-- vention.

As aforestated, it is desirable that all of these problems be solved by means of mechanism simple in construction, capable of being reliably manufactured in quantity, and possessing long usage life under severe operating conditions. The selector structure of the present invention is designed to meet these additional desiderata.

To the accomplishment of the foregoing and I such other objects as may hereinafter appear,

the invention further consists in the structural combinations hereinafter sought to be defined in the claims and described more in detail hereinbelow in connection with the appended drawings, in which:

Fig. 1 is a vertical elevational view of the radio station selector of the present invention, with parts shown in section as indicated in the planes of the broken line l| of Fig. 2;

Fig. 2 is a plan view thereof, with certain parts broken away and other parts shown in cross-section;

Fig. 3 is a view thereof, taken in cross-section in the planes of the broken line 3- 3 of Fig. 2;

Fig. 4 is a view similar to Fig. 3, with the parts shown in a different position;

Fig. 5 is a fragmentary view taken in crossseotion in the planes of the broken line 5-5 of Fig. 3;

Fig. 6 is an enlarged view taken in cross-section in the plane of the line 6-5 of Fig, 2

Fig. '7 is an enlarged view, with parts shown in section, of one of the push-button elements of the mechanism, the section being along the line 'l--'I of Fig. 6;

Fig. 8 is a view of the detail, showing the latching of a push-button element;

Fig. 9 is a view of a detail taken in cross-section in the plane of the line 9-9 of Fig. 3; and

Fig. 10 is a view showing a modification of the arrangement between the selector mechanism and the tuning unit.

Referring now more in detail to the drawings, the radio station selector of the present invention comprises a unit embodying a supporting frame F with which is fixedly associated the tuning unit T such as a variable condenser, the said frame F supporting all of the elements of the selector system. The essential components of the selector system comprise an operating member 0 connected by means of a linkage mechanism L to the rotor of the tuning unit T, the said operating member 0 being common to and being actuatable by any of a plurality of push-button manuals all collectively designated as M. These components of the selector system are designed as aforesaid to readily convert and multiply short linear movements of the push-button elements into a 180 degree rotation of the rotor of the tuning unit and to do this with that freedom of play and back lash and with that minimum of friction loss which will permit the obtaining of the referred to high accuracy repeat operations.

The frame F is built in simple fashion to provide a firm and rigid support. It consists of front and rear walls I2 and I3, an. intermediate brace wall ll, all bolted by suitable attaching means such as screws I5, 15 to the side walls 16 and H. The rear and intermediate walls 13 and II 'have suitable ledges I3, I I turned down from the top edges thereof to provide a support for the condenser unit T, which latter may be secured thereto in any approved way as by means of the attaching screws 18 (see Figs. 3 and 4). The tuning unit T may be of any modern type; and this is illustrated in Figs. 1 and 2 as a condenser of the two or more gang type having a plurality of stator sections 8, and a plurality of rotor sections 1' united to .form a single rotor having an operating shaft 19. The rotor of the condenser is movable over its entire 180' degree tuning range between the positions shown in Figs. 3 and 4 of the drawings.

One of the most important components of the selector mechanism is the means for linking the operating member 0 to the tuning rotor r. The operating member 0 is designed to be movable over an arc of about 45 degrees, and, therefore, the means for linking the operating member to the tuning rotor is made to comprise a mechanism for multiplying the 45 degree rotation of the operating member 0 to cover the 180 degree range of movement of the tuning rotor 1'. To controllably eliminate back lash in this part of the selector and to reduce the friction loss to a minimum, and also to provide for a simplified mechanical structure, the invention at this point includes connecting the operating member 0 to the condenser rotor r by a motion multiplying linkage mechanism embodying three elements, with the relatively movable parts thereof localized to two pivot points at which back lash or play is controllably eliminated. This motion multiplying mechanism comprises a long outer element or arm 20 fixed at its outer end to the operating member O, a short outer element or arm 2| fixed at its outer end to the rotor shaft [5, and a link or intervening element 22 pivotally connected to the outer elements or arms '20 and 2|. This threeelement linkage mechanism is movable between the extremes of an open link formation as shown in Fig. 4 of the drawings to a convolute link formation as shown in Fig. 3 of the drawings. This linkage mechanism and this described motion thereof enables the desired conversion of a short (45 degrees) arcuate motion of the operating member, to the full range degrees) are motion of the condenser rotor.

In detail, the operating member 0 consists of a contact plate 23 having a cam or contact face 24 and provided at its opposite ends with the supporting hubs 25 and 26 rigidly united to a shaft 21, the latter rotating in suitable bearings 28 and 29 fitted to the sidewalls l6 and I1 respectively of the frame F. The long arm 20 of the linkage mechanism L is riveted at its outer circular end to the supporting hub 26 of the operating member as best shown in Fig. of the drawings. The short .arm 2| is fixedly attached to the rotor shaft. I9 by any conventional means such as the collar and set screw 30. The link or intervening member 22 is pivotally attached to the arms 2?] and 2| by means of the pivot pins 3| and -32 see particularlyFig. 5)'-. Thus, the operating member 0 'is fixedly united or linked to the condenser rotor r, except for the two pivot pins 3| and 32,. where all the loose play or backlash may be and is thus localized. The

play at these pivot pins 3| and 32 is then elim."

inated by additionallycoupling the outer elements or arms and 2| by means of the tensioning spring 33 arranged in parallel with the tween-the operating member and. the tunable rotor to a minimum. It will be noted that the linkage elements are also exceedingly simple in structure and may be readily assembled for use, thus enabling the manufacture of these parts with uniformity in quantity production.

The push-button manuals, collectively desighowever) the key having a substantial height or vertical dimension. With this construction, eventhough there isslight'play of the key in the keyways, (enabling the obtaining of a low friction loss) there is substantially no rotational componentof this play. By means of this structure, the efiective play may be localized at a single point; and the relation between the manual 7 and the operating member of the exemplified structure is made such that the play may be localized, controlled and eliminated at the bottom of the keyway' 36 indicated at a: in Fig.- 6.

This will be explained further hereinbelow in connection with a description of the operation of the manualshown in Figs.'3 and 4 of the drawings.

As aforestated, provision is made to enable the i new to adjust or readjust the push-button manuals to desired frequencies or stations and it is an object of the present invention to provide aconstruction in which the adjustment may be made from the outside of the radio cabinet. To accomplish this, each-manual is provided with an adjusting element 33, the inner end of which controls the position of the contact member 33 and the outer end of which projects from the frame F'and from the radio cabinet C (see Figs.

3 and 4) so as to be accessible to the user when adjustment is desired to be made.

The adjusting element 33 specifically consists of a rod-like element which directly carries at its inner end the contact member 38, which latter is in the form of a ball, and which is pronated as M, comprise a plurality of push-button elements each representing a given frequency or station and each linearly or translationally mov able to actuate the operating member 0, which latter is common to all of the push-button elements. In the exempliflcation of the invention shown in the drawings, eight push-button elements are shown, seven of which are employed for. preselecting given stations or frequencies,

and one of which (the right end one of Figs. 1 and 2) is employed when it is desired to operate the tuning unit to any point in its tuning range. Since, except for the position of the adjusted parts, the first seven push-button elements are identical in structure and operation,

only one of these need be described,such a one being shown in enlarged detail in Figs. 6 and 7 of the.drawings. The eighth manual used to cover the full tuning range of the condenser is shown in detail-in Figs. 3 and 4 of the drawings.

Referring generally to Figs. 1 and 2, and particularly to Figs. 6 and 'l of the drawings, each push button manual comprises a key 34 slidable in keywa'ys 35'and 36 cut in the front and brace walls l2 and 4 respectively of the frame F, the, said key 34 being provided at its front end with an operating button 31 and at its rear end with a contact member 38, the said contact memberbeing intended for cooperation with the contact or camface 24 of the operating member plate 23.. In the drawings, these keys are shown in their retracted or inoperative position.

The structure and operation of each pushbutton manual and its relation to the operating member 0 are so designed that all play is deflnitely localized and made controllable and then eliminated at the control points. To avoid any perceptible rotational component of play, the push-button manuals are made responsive only to a translational slidable movement. This is preferably accomplished by making each key from sheet material (of relatively thick stock,

vided at its forward end with a screw-threaded portion 43. The adjusting element 39 is supported for rotation and longitudinal movement on the key 34 in any desired way. As shown, the

key 34 is concaved at its middle portionto receive the adjusting element 33, and. two U-shaped retainingsprings 4| and 42 anchored to the key,

are employed to support the adjusting element for the desired movement. The retaining springs are constructed so that they offer considerable force to hold the adjusting element 39 in any adjusted position, and of these, the retaining spring 4| is utilized-so that its two down-tumed branches 4| and 4| mate with the thread in the threaded portion of the adjusting element.

The operating button 31 received by the two lugs 34 and 34 of the key 34 is centrally bored at 31', thisbore being in alignment with the adjusting element 33. Each push-button 31 is also recessed at its front end at 31 to receive a station identifying plate 43. With this described construction, when the identifying plate 43 is removed, a screw driver may be inserted through the bore 31' of the push-button 3'! to engage the head of the screw portion 40 of the adjusting element to rotate the latter and efiect incremental longitudinal movements thereof. Preferably, the adjusting element of each of the manuals is longitudinally movable on the manual over a distance which will cover the full range of adjustment or movement of the rotor of the tuning element.

Associated with all of the manuals is a latch member for locking the manual in an operative position, and the said latch member serves to determine not only the'operative position of the manual, but also the finally assumed position of the rotor of the tuning unit. This latch member consists of a curved plate 44 supported by means-of two integral trunnions 45 and 43 in apertures in the side walls It and n of the frame F. To cooperate with the bottom tooth-like end of the latch ,each key is provided with a cam tooth 41 acting both for moving the latch member to an unlatching position and for engaging the latch member to lock the manual in an operative position. The accomplishment of 'these functions is respectively accomplished by the cam face 48 and the locking face 49 of the tooth l1. The latch is urged to the position of engagement with the parts of the tooth 41 by means of a spring 50 (see Fig.. 2) the ends of which are anchored to the ledge I2 of the front frame wall I2 and the latch member 44. Each key is also provided with a hairpin type of spring 5| freely anchored at its opposite ends to the brace plate M of the frame F and to the key 34 by being received in suitable apertures in these parts, as is most clearlyshown in Fig. 6 of the drawings. Each key may also be provided with a stop lug 52 which engages a cushion stop plate 53 mounted on the front wall ii of the frame F. With this described construction, an inward push applied to the button 31 of the manual produces, first, an engagement between the ball contact member 38 and the contact plate 23 of the operating member 0, and then the desired actuation of the operating member 0, the finally assumed position of these parts being determined by the engagement between the latch member and the latch face 49 of the key tooth 41 as best illustrated in Fig. 8 of the drawings. The contact engagement betweenthe contact member 38 and the contact plate 23 is effected by means of a spring 54 (see particularly Figs. 3 and 4) anchored at its opposite ends to the frame side wall I! and the linkage arm 20, the anchorage points being such that the spring operates to urge the elements of the linkage mechanism L to the folding up or convolute condition shown best in Fla. 3 of the drawings. This spring is freely or pivotally anchored in the frame wall I! so that a substantially constant tension is applied to the rotor of the tuning unit irrespective of its tunedwill be obvious that the initial inward movement ating knob for rotating the adjusting element of the manual. The parts of this manual, which are similar to those of the manual shown in Figs. 6 and 7 of the drawings, are designated by similar reference characters, and the description thereof given above applies equally thereto, ex-

cept that the screw-threaded portion 40 of the with a flat extension 80 which is received by a correspondingly shaped orifice in the knob shank 51, the construction being such that when the knob is rotated, the adjusting element is caused to rotate therewith and is constrained to move longitudinally with respect to said shank. The shank and knob are held to the button 59 in any approved way, and in the structure shown, this is accomplished by the provision of. the U-shaped member 6!, the branches of which are held in grooves 62 of the push-button 51, the said branches also riding in a. circular groove 63 in i the knob shank 51. It will be understood that to operate this manual, it first has to be pushed (in the same way as the other manuals) from a position shown in Fig. 3 of the drawings to that shown in Fig. 4 of the drawings. With this manual thus pushed into its operative and latched position shown in Fig. 4, the knob 56 may be rotated to move the rotor of the tuning unit to any point of its range so that any desired station may be tuned in by the operator. It will also be apparent that upon operation thereafter of any of the other presetting manuals, the latch 44 will be automatically moved to release the push-button manual shown in Figs. 3 and 4 to the retracted or inoperative position.

It will now become clear that the designed construction and operation of the manuals enables (as do the construction and operation. of the operating means and the linkage mechanism) the localizing of the play and the control and elimination thereof, all to the end of securing the high tuning and repeat accuracy described. By referenceto Fig; 4 of the drawings, it willbe seen that the operating contact plate 18 is so related to the contact ball 3|, that the tangentangle of contact of the operating plate and the contact ball is at all times such as to cause a downward thrust of the key 34, driving this key to eliminate the play therein at the point a: (see Figs. 4 and 6). Furthermore, the key return spring I is so positioned that it imparts a combined downward and outward thrust to the key II. The play is thereby localized to the point a: and eliminated by this means at this point..

In Fig. 10 of the drawings, there is shown a modification of the arrangement between the selector mechanism and the tuning unit. In

Fig. 1, the tuning unit is shown mounted on the top of the selector frame, whereas in Fig. 10 the tuning unit T is shown mounted at the rear of the selector frame F. This rearrangement is depicted to exemplify another desirable characteristic of the three-element linkage mechanism L, this linkage mechanism being capable of multiplying the motion of the operating member 0' to the required large arc rotation of the tuning unit rotor, whether or not the tuning unit is attached to the selector frame and in different relative positions" of the tuning unit and the frame. The elements of the linkage mechanism L' in Fig. 10

' are shown in the wound up or convolute position adjusting element 38 is preferably made with a larger screw pitch to enable coarser adjustments to be made.

This manual is provided with anv operating knob 56 having a shank 51 received in the bore 50 of the push-button 59, which latter is secured to the key in the same way as described for the key shown in Figs. 6 and '7 of the drawings. The adjusting rod 39 is provided at its forward end correspondingto the position shown in Fig. 3 of the drawings.

To relieve the condenser rotor from all shock at its extreme positions (shown in Figs. 3 and 4) stop means may be provided, eifective on any part of the operating means of the selector mechanism. Such stop means may be made effective, for example, on the short arm 2| of the linkage mechanism L, and may comprise a plate-shaped standard 64 ailixed to the frame side wall H, the said standard being'provided at its upper ends with the turned-in lugs II and 86 arranged in th path of movement of the arm 2! of the linkage mechanism L, as clearly shown in Figs. 4 and 3 inch) linear or translational movement operates the selector mechanism to rotate the condenser rotor to any preset position within its 180 degree rotation range. This operation is accomplished, by simple mechanism inter-related so that there is substantial freedom of playand back lash and a minimum of friction loss, all to the end that there may be obtained a high degree of total accuracy in the repeated operations of the manuals. All but one of of the manuals M are operable for preselecting a frequency or station, although any one of these may also be manipulated by operation of its adjusting means to tune the tuning unit to any desired frequency. One of these manuals is set apart from the others and is specially designed for tuning the condenser rotor to any desired station. When the user or operator desires to adjust or readjust the manuals, he may do so from the outside of the cabinet. No gears are employed in the mechanism of the selector; and the elements of the operating mechanism of the selector are so designed by their uniformity and simplicity as to be capable of being manufactured in large quantities and assembled with facility and rapidity. Moreover, all ofthe operatingvelements are rugged in construction and are subject to very little wear and tear in the repeated operations to which a selector of this character is normally subjected, thereby afiording long usage life. All of the parts are readily accessible for repair or replacement.

It will be understood that one of the preferred forms of the invention has been shown and described to exemplify the principles of the invention, and that numerous changes may be made thereto without departing from the spirit of the invention defined by the appended claims.

We claim:

1; In a radio station selector, 'a station tuning device having a stator and a rotor, said rotor being movable over a relatively large are, a rotatable operating member selectively operable by selective actuation of a plurality of manuals, said operating member being movable over a relatively small arc, and a three-element motionmultiplying linkage mechanism connecting said operating member with said rotor, the outer elements of said linkage mechanism being connected at their outer ends to said operating member and rotor andthe intervening element of said linkage mechanism being pivotally connected to said outer elements, and a tensioning means in paral- I lel with said intervening element coupling toing movable over a relatively large arc, a rotatable operating member selectively operable by selective actuation of a plurality of manuals, said operating member being movable over a relatively small arc, and a motion-multiplying linkage mechanism connecting said operating member with said rotor, said mechanism including two elements connected at their outer ends to said operating member and rotor and pivotally coupled together at their inner ends, and a tensioning means, in parallel with said pivotal coupling, for coupling together said elements, said linkage mechanism being movable between the extremes of an open link formation and a convolute link formation.

A SAMUEL COHEN. 

